SECRET phone taps are believed to have been used in the bombshell Darren Weir police inquiry.

It is understood phone intercepts have formed part of the sporting integrity intelligence unit probe into Weir's activities.

Police are following multiple lines of lines of inquiry but have not yet decided if they will charge Australia's largest trainer.

Weir is expected to be disqualified for four years at a Racing Appeals and Disciplinary Board hearing Wednesday over the possession of three jiggers, or electronic apparatus, allegedly used for shocking horses.

The phone tap revelations show the wide-ranging nature of a police inquiry which is also understood to involve video surveillance at a Weir stable.

Racing Victoria investigators had been running the jigger inquiry for 18 months before it was referred to police in August last year.

RV officials do not have the powers to carry out some intrusive investigative functions such as tapping phones.

Victoria Police, accompanied by Australian Federal Police and racing integrity operatives, executed warrants at properties near Warrnambool and Ballarat last Wednesday.

The raid uncovered the jiggers, an unlicensed firearm and a substance believed to be cocaine.

The Weir police inquiry goes well beyond the alleged use of jiggers.

Victoria Police has stated that one element of the investigation relates to "engaging in conduct that corrupts or would corrupt a betting outcome".

Another is the "use of corrupt conduct information for betting purposes."

Such matters - if police push ahead - would most likely be sent to the Office of Public Prosecutions for advice on charges.

Racing is awash with rumours of a video involving alleged maltreatment of a horse on a treadmill.

Racing integrity chief Jamie Stier said RV was not in possession of the video, but encouraged members of the public with information to contact them or police.

There is also speculation the phone taps might have intercepted conversations with licensed personnel, including jockeys.

Weir faced the RV stewards in a marathon hearing on Monday night.

That inquiry is not believed to have delved into betting issues.

Police have indicated there is nothing to support rumours that they are investigating drug-related offences linked to the Weir matters.